This is an implementation of two WL items:

- WL#3158: IM: Instance configuration extensions;
  - WL#3159: IM: --bootstrap and --start-default-instance modes

The following new statements have been added:
  - CREATE INSTANCE;
  - DROP INSTANCE;

The behaviour of the following statements have been changed:
  - SET;
  - UNSET;
  - FLUSH INSTANCES;
  - SHOW INSTANCES;
  - SHOW INSTANCE OPTIONS;

server-tools/instance-manager/instance.h

@@ -17,7 +17,10 @@
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
 #include <my_global.h>
+#include <m_string.h>
+
 #include "instance_options.h"
+#include "priv.h"
 
 #if defined(__GNUC__) && defined(USE_PRAGMA_INTERFACE)
 #pragma interface
@@ -25,31 +28,120 @@
 
 class Instance_map;
 
+
+/*
+  Instance_name -- the class represents instance name -- a string of length
+  less than MAX_INSTANCE_NAME_SIZE.
+
+  Generally, this is just a string with self-memory-management and should be
+  eliminated in the future.
+*/
+
+class Instance_name
+{
+public:
+  Instance_name(const LEX_STRING *name);
+
+public:
+  inline const LEX_STRING *get_str() const
+  {
+    return &str;
+  }
+
+  inline const char *get_c_str() const
+  {
+    return str.str;
+  }
+
+  inline uint get_length() const
+  {
+    return str.length;
+  }
+
+private:
+  LEX_STRING str;
+  char str_buffer[MAX_INSTANCE_NAME_SIZE];
+};
+
+
 class Instance
 {
+public:
+  /*
+    The following two constants defines name of the default mysqld-instance
+    ("mysqld").
+  */
+  static const LEX_STRING DFLT_INSTANCE_NAME;
+
+public:
+  /*
+    The operation is intended to check whether string is a well-formed
+    instance name or not.
+  */
+  static bool is_name_valid(const LEX_STRING *name);
+
+  /*
+    The operation is intended to check if the given instance name is
+    mysqld-compatible or not.
+  */
+  static bool is_mysqld_compatible_name(const LEX_STRING *name);
+
 public:
   Instance();
 
   ~Instance();
-  int init(const char *name);
+  int init(const LEX_STRING *name_arg);
   int complete_initialization(Instance_map *instance_map_arg,
-                              const char *mysqld_path, uint instance_type);
+                              const char *mysqld_path);
 
   bool is_running();
   int start();
   int stop();
   /* send a signal to the instance */
   void kill_instance(int signo);
-  int is_crashed();
+  bool is_crashed();
   void set_crash_flag_n_wake_all();
   Instance_map *get_map();
 
+  /*
+    The operation is intended to check if the instance is mysqld-compatible
+    or not.
+  */
+  inline bool is_mysqld_compatible() const;
+
+  /*
+    The operation is intended to check if the instance is configured properly
+    or not. Misconfigured instances are not managed.
+  */
+  inline bool is_configured() const;
+
+  inline const LEX_STRING *get_name() const;
+
 public:
   enum { DEFAULT_SHUTDOWN_DELAY= 35 };
   Instance_options options;
 
 private:
-  int crashed;
+  /* This attributes is a flag, specifies if the instance has been crashed. */
+  bool crashed;
+
+  /*
+    This attribute specifies if the instance is configured properly or not.
+    Misconfigured instances are not managed.
+  */
+  bool configured;
+
+  /*
+    This attribute specifies whether the instance is mysqld-compatible or not.
+    Mysqld-compatible instances can contain only mysqld-specific options.
+    At the moment an instance is mysqld-compatible if its name is "mysqld".
+
+    The idea is that [mysqld] section should contain only mysqld-specific
+    options (no Instance Manager-specific options) to be readable by mysqld
+    program.
+  */
+  bool mysqld_compatible;
+
   /*
     Mutex protecting the instance. Currently we use it to avoid the
     double start of the instance. This happens when the instance is starting
@@ -66,4 +158,22 @@ private:
   void  remove_pid();
 };
 
+
+inline bool Instance::is_mysqld_compatible() const
+{
+  return mysqld_compatible;
+}
+
+
+inline bool Instance::is_configured() const
+{
+  return configured;
+}
+
+
+inline const LEX_STRING *Instance::get_name() const
+{
+  return &options.instance_name;
+}
+
 #endif /* INCLUDES_MYSQL_INSTANCE_MANAGER_INSTANCE_H */